[1] | 1 | ////////////////////////////////////////////////////////////////////////// |
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| 2 | // example_PythiaStreamIO.cc |
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| 3 | // |
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| 4 | // garren@fnal.gov, May 2009 |
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| 5 | // |
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| 6 | ////////////////////////////////////////////////////////////////////////// |
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| 7 | /// example of generating events with Pythia using HepMC/PythiaWrapper.h |
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| 8 | /// Events are read into the HepMC event record from the FORTRAN HEPEVT |
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| 9 | /// common block using the IO_HEPEVT strategy |
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| 10 | /// |
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| 11 | /// To Compile: go to the HepMC example directory and type: |
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| 12 | /// make example_PythiaStreamIO.exe |
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| 13 | /// |
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| 14 | /// This example uses streaming I/O |
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| 15 | /// writePythiaStreamIO() sets the cross section in GenRun |
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| 16 | /// readPythiaStreamIO() reads the file written by writePythiaStreamIO() |
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| 17 | /// |
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| 18 | ////////////////////////////////////////////////////////////////////////// |
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| 19 | |
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| 20 | |
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| 21 | #include <fstream> |
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| 22 | #include <iostream> |
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| 23 | #include "HepMC/PythiaWrapper.h" |
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| 24 | #include "HepMC/IO_HEPEVT.h" |
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| 25 | #include "HepMC/GenEvent.h" |
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| 26 | #include "PythiaHelper.h" |
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| 27 | |
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| 28 | void writePythiaStreamIO(); |
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| 29 | void readPythiaStreamIO(); |
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| 30 | |
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| 31 | int main() { |
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| 32 | |
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| 33 | writePythiaStreamIO(); |
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| 34 | readPythiaStreamIO(); |
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| 35 | |
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| 36 | return 0; |
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| 37 | } |
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| 38 | |
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| 39 | |
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| 40 | void writePythiaStreamIO() { |
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| 41 | // example to generate events and write output |
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| 42 | std::cout << std::endl; |
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| 43 | std::cout << "Begin pythia_out()" << std::endl; |
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| 44 | //........................................HEPEVT |
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| 45 | // Pythia 6.1 uses HEPEVT with 4000 entries and 8-byte floating point |
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| 46 | // numbers. We need to explicitly pass this information to the |
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| 47 | // HEPEVT_Wrapper. |
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| 48 | // |
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| 49 | HepMC::HEPEVT_Wrapper::set_max_number_entries(4000); |
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| 50 | HepMC::HEPEVT_Wrapper::set_sizeof_real(8); |
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| 51 | // |
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| 52 | //........................................PYTHIA INITIALIZATIONS |
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| 53 | initPythia(); |
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| 54 | |
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| 55 | //........................................HepMC INITIALIZATIONS |
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| 56 | // |
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| 57 | // Instantiate an IO strategy for reading from HEPEVT. |
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| 58 | HepMC::IO_HEPEVT hepevtio; |
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| 59 | // |
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| 60 | { // begin scope of ascii_io |
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| 61 | // declare an output stream |
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| 62 | const char outfile[] = "example_PythiaStreamIO_write.dat"; |
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| 63 | std::ofstream ascii_io( outfile ); |
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| 64 | if( !ascii_io ) { |
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| 65 | std::cerr << "cannot open " << outfile << std::endl; |
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| 66 | exit(-1); |
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| 67 | } |
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| 68 | // use the default IO_GenEvent precision |
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| 69 | ascii_io.precision(16); |
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| 70 | // write the line that defines the beginning of a GenEvent block |
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| 71 | HepMC::write_HepMC_IO_block_begin( ascii_io ); |
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| 72 | // |
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| 73 | //........................................EVENT LOOP |
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| 74 | for ( int i = 1; i <= 100; i++ ) { |
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| 75 | if ( i%50==1 ) std::cout << "Processing Event Number " |
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| 76 | << i << std::endl; |
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| 77 | call_pyevnt(); // generate one event with Pythia |
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| 78 | // pythia pyhepc routine converts common PYJETS in common HEPEVT |
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| 79 | call_pyhepc( 1 ); |
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| 80 | HepMC::GenEvent* evt = hepevtio.read_next_event(); |
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| 81 | // define the units (Pythia uses GeV and mm) |
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| 82 | evt->use_units(HepMC::Units::GEV, HepMC::Units::MM); |
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| 83 | // add some information to the event |
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| 84 | evt->set_event_number(i); |
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| 85 | evt->set_signal_process_id(20); |
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| 86 | // set number of multi parton interactions |
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| 87 | evt->set_mpi( pypars.msti[31-1] ); |
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| 88 | // set cross section information |
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| 89 | evt->set_cross_section( HepMC::getPythiaCrossSection() ); |
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| 90 | // write the event out to the ascii files |
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| 91 | ascii_io << (*evt);; |
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| 92 | // we also need to delete the created event from memory |
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| 93 | delete evt; |
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| 94 | } |
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| 95 | // write the line that defines the end of a GenEvent block |
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| 96 | HepMC::write_HepMC_IO_block_end( ascii_io ); |
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| 97 | //........................................TERMINATION |
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| 98 | // write out some information from Pythia to the screen |
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| 99 | call_pystat( 1 ); |
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| 100 | } // end scope of ascii_io |
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| 101 | } |
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| 102 | |
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| 103 | void readPythiaStreamIO() { |
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| 104 | // example to read events written by writePythiaStreamIO |
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| 105 | // and write them back out |
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| 106 | std::cout << std::endl; |
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| 107 | // input units are GeV and mm |
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| 108 | const char infile[] = "example_PythiaStreamIO_write.dat"; |
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| 109 | std::ifstream is( infile ); |
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| 110 | if( !is ) { |
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| 111 | std::cerr << "cannot open " << infile << std::endl; |
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| 112 | exit(-1); |
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| 113 | } |
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| 114 | // |
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| 115 | { // begin scope of ascii_io |
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| 116 | // declare an output stream |
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| 117 | const char outfile[] = "example_PythiaStreamIO_read.dat"; |
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| 118 | std::ofstream ascii_io( outfile ); |
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| 119 | if( !ascii_io ) { |
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| 120 | std::cerr << "cannot open " << outfile << std::endl; |
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| 121 | exit(-1); |
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| 122 | } |
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| 123 | ascii_io.precision(16); |
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| 124 | HepMC::write_HepMC_IO_block_begin( ascii_io ); |
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| 125 | // |
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| 126 | //........................................EVENT LOOP |
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| 127 | HepMC::GenEvent evt; |
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| 128 | int i = 0; |
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| 129 | while ( is ) { |
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| 130 | evt.read( is ); |
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| 131 | // make sure we have a valid event |
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| 132 | if( evt.is_valid() ) { |
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| 133 | ++i; |
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| 134 | if ( i%50==1 ) std::cout << "Processing Event Number " |
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| 135 | << i << std::endl; |
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| 136 | if ( i%25==2 ) { |
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| 137 | // write the cross section if it exists |
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| 138 | if( evt.cross_section() ) { |
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| 139 | std::cout << "cross section at event " << i << " is " |
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| 140 | << evt.cross_section()->cross_section() |
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| 141 | << std::endl; |
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| 142 | } |
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| 143 | } |
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| 144 | // write the event out to the ascii files |
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| 145 | evt.write( ascii_io ); |
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| 146 | } |
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| 147 | } |
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| 148 | //........................................TERMINATION |
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| 149 | HepMC::write_HepMC_IO_block_end( ascii_io ); |
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| 150 | } // end scope of ascii_io |
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| 151 | } |
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